Folding carton lock



' Nov. 14, 1961 M. J. LAWRENCE 3,008,626

FOLDING CARTON LOCK Filed June 2, 1958 2 Sheets-Sheet 1- fil wj 61 61 .ZZZYEHZUI 13 zwmafy'w Nov. 14, 1961 M. J. LAWRENCE $008,626

FOLDING CARTON LOCK Filed June 2, 1958 2 Sheets-Sheet 2 2530M Ma famar United States Patent 3,008,626 FOLDING CARTON LOCK Michael J. Lawrence, Chicago, Ill., assignor to Chicago Carton Company, a corporation of Delaware Filed June 2, 1958, Ser. No. 739,296 6 Claims. (Cl. 229-31) The present invention relates generally to foldmg cartons and more particularly to a novel locking means for fastening together overlying sheet material. In this regard, the novel locking means finds exceptional utility in the construction of folding cartons.

In the past, various means have been employed in the folding carton field for securing together overlying flexible sheet material such as paperboard or the like. Some of these methods have included stapling, gluing, or the interconnection of overlapping flaps having edges with cooperating notches. The present invention is particularly directed to a new and improved arrangement for interlocking flexible sheet material in face to face relation. The novel locking structure disclosed herein has many desirable advantages, among which are its neat appearance, reliable resistance to disengagement, and simple assembly in locking arrangement.

Accordingly, the principal object of the present invention is the provision of a novel arrangement for fastening together flexible sheet material arranged in face to face relation.

Another object of the present invention is the provision of an improved carton which includes such novel locking means to maintain the carton in erected condition.

Still another object of the present invention is to provide an improved folding carton which includes a novel arrangement for locking the panels thereof in position and for securing the cover in closed relation to the carton to thereby present a sturdy, neat package which may be directly marketed to the consumer or may be subsequently repackaged as desired. 1

A further object of the present invention is the provision of a folding carton of the type described which may be readily set up immediately prior to use and which is of strong and durable construction to withstand a substant-ial amount of rough handling and yet is of simple andeconomical manufacture.

Other objects and advantages of the present invention will be understood by reference to thefollowing description and the accompanying drawings wherein there is illustrated two embodiments of a carton constructed in accordance with the present invention.

In the drawings:

FIGURE 1 is-a plan view of a blank from which a carton, embodying various features of the present invention, may be formed;

FIGURE 2 is a perspective view of a carton erected from the blank shown in FIGURE 1, with one of the corners shown unfastened in order to more clearly illustrate the locking means employed;

FIGURE 3 is a plan view of a blank from which a modified form of a carton, embodying various features of the present invention, may be erected; and

FIGURE 4 is a perspective view of a carton erected from the blank shown in FIGURE 3, with a portion broken away and with one of the corners shown unfastened in order to illustrate the locking arrangement therefor.

In the practice of the present invention, a pair of overlapping sheets of flexible material may be elfectively secured together by a simple and novel locking arrangement. The locking structure comprises generally apair of spaced-apart, generally parallel slits or cuts in one of the sheets, and a tab extending from the other sheet having a portion thereof with a width greater than the Ice distance between the slits. The tab is disposed in locked engagement with the first sheet by projecting the side marginal regions thereof through the slits and into adjoining relation with the marginal areas adjacent the slits on the exposed surface of the first sheet. In one preferred arrangement, illustrated in the drawings, the parallel slitsare provided with a cross slit to form a cut of generally H-shape. The cross cut permits greater ease in insertion of the margins of the tab through the slits and also provides for a covering flap to close any gap formed by the insertion of the tab.

The improved locking arrangement of the present invention may be advantageously employed in a wide variety of structures. However, distinct advantages are achieved by utilization of the features of the improved locking arrangement in folding cartons, and more particularly in a leak-proof folded carton, such as shown in FIGURE 2, which has particular advantageous application in the packaging of frozen foods.

The carton 11, shown generally in FIGURE 2, is formed from the blank 13 illustrated in FIGURE 1. The various walls of the carton and the panels of the blank from which the walls are formed are referred to with identical reference numbers. In view of the fact that the carton 11 is intended for use in the frozen food industry, it is of generally leak-proof construction, and accordingly, the paperboard employed is of the water-proof type. Various suitable paperboards are presently available for this purpose, and it will be further understood that paperboard now or hereafter available may be employed.

The blank 13 is of generally rectangular form, and includes centrally therein a rectangular bottom panel 15 which is foldably joined to front and rear side wall panels 17 and 19 through suitable fold or score lines 21 and 23, respectively. End wall panels 25 and 27 are also foldably joined to the bottom panel 15 through suitable score lines 29 and 31, respectively, A cover panel 33- extends from the outer edge of the rear side wall panel 19 and is hingedly connected thereto along a score line 35. Each of the end wall panels 25 and 27 has joined thereto along suitable fold lines 41 and 43 a pair of closing flaps 37 and 39, respectively. In addition, a flap 45 is joined to the outer edge of the front side wall panel 17 along a suitable scoreline 47. -Finally, located adjacent each of the corners of the bottom panel 15 is a corner member or gusset indicated at 49, 51, 53 and 55, respectively, which is integrally and foldably connected to the ends of the adjacent end and side wall panels through respective extensions 21a, 23a, 29a and 31a of the fold lines 21, 23, 29 and 31.

A score or fold line 57 extends generally diagonally of each of the gussets from the gusset corner adjacent the bottom panel to adjacentthe opposed gusset corner. Each of the gussets is formed with a tab 59 for interlocking action with an adjoining carton panel. The tabs 59 extend generally outward of the gusset edges which are in general alignment with the outer edge of the adjacent end wall panel 25 or 27 and are hingedly connected to said gussets along suitable fold lines 61.

I The flap 45 and the cover panel 33 are formed with suitable tab receiving and locking means for fastening the gussets to the carton walls to maintain the carton in erected condition. The preferred construction illustrated includes a pair of H-shaped slit formations 63 in both the flap 45 and cover panel 33. Each of the H-shaped slit formations 63 is generally identical, and includes a pair of parallel cut lines 65 and 67, which are interconnected by a perpendicular cross cut line 69. The parallel cutlines 65 and 67 extend in generally perpendicular re-- Y lation from the adjacent associated fold lines 35 or 47. In this connection, best results have been achievedby locating the cross cut line 69 at a distance from the ends of the parallel cut hues 65 and 67 adjacent the associated fold hues somewhat greater than half and preferably about two-thirds of the length of the upright cut lines 65 and 67. In this manner, a lower or base displacea-ble portion 71 is defined extending to one side of the out line 69 between the parallel cut lines 65 and 67, and an upper or covering disp-laceable portion 73 is formed between the parallel cut lines 65 and 67 to the other side of. the cross out line 69. Provision of the cross cut line 69 results in the desirable advantages of increased ease in insertion of the tabs 59' within the slit formations 63 and affords closure of gaps in the outer surface by means of the upper or covering displaceable portion 73.

Each of the tabs 59 which are interlocked with the H-shaped slit formations 63 to maintain the carton erect is formed with a neck defined by the score line 61 having a width approximating the width between the parallel cut lines. The sides of the tab extend in divergent angular relation outwardly from the neck and then parallel to each other to thereby form a generally rectangular tab having a width greater than the width between the parallel cut lines 65 and 67 and a height greater than the height ofthe lower displaceable portion 71 but not greater than the overall height of the parallel cut lines 65 and 67.

Good results have been achieved by forming the tabs 59 with a height which" projects approximately to the mid section of the upper displacea-ble portion 73.

Of course, various other slit formations and tab configurations may readily be employed and still secure various of the advantages of the present invention. One such arrangement might include a: tab interlocking with a panel having, a displaceable flap'formed in part bya pair ofparallel cuts which extend from a base fold line and may be-formed at their other end in any suitable configuration. In this connection, of course, the size of the tab should be proportioned-so asto-be displaceable cut lines eXtending in perpendicular relation from a fold line,'it should beunderstoodthat the presence and utilizationot such a. fold line is not necessarily essential to the presentinvention, butrepresents a preferred form thereof inorder to facilitate displacementof the adjacent lower'flap.

Acarton of the present type maybe closedafterfilling with the desired food product by a variety of means. Howeventhe arrangement illustrated provides aclosure lock which is simple to fabricate, which alfords excellentlocking, action,- and which, in combination with the gusset lockingv arrangement, providesan unusually strong and neat appearing package.

As shownin the-blank 1-3, a cover panel locking't-ab or tuck 77 isfoldably connected-alongafold line 79-to the outeredge of the cover panel 33; The tuck 77' may be of any-suitable shape, and as shown, is of generally rectangularform having; two converging sides; The fold line 79 joining the locking tuck 77 to the-cover panel-33 is-spacedslightly inwardly of andparallel to the outer edge of thev cover panel'33-and has at each end thereofanotch-or slit 81which includes acurvednortionextendingv into alignment with the outer edge" of the cover panel and'whi'oh' forms anea'r 83 on the locking tuck adjacent each of the ends of the. fold line 7-9.

Provided in'the flap 45 extending from the front side wal-l panel 17 is: a slit 85 which; incident t'o'the subsequent'inward foldingof the flap 45; forms a slot or opening:87' for receiving and locking the cover panel tuck 7 7.

In this regard, thecenterportion of-thefold line 47 joining theflap45 tome-front side-panel 17 is interrupted by the-slit 85: which joins the innerv ends: thereof; The slit includes a segment 87 at each end thereof in alignment with the fold line 47, curved portions 89 which extend inward of the flap 45 from each of the segments 87, and a central segment 91 which joins the curved portions 89 and is generally parallel to the fold line 47. The length of the central segment 91 is approximately equal to the length of the outer edgeinoluded between the converging sides of the cover panel locking tuck 77'.

The engagement of the cover lock,. and the interlock between the gusset tabs and the slit formations are best illustrated when the carton is in erected condition. Accordingly, a preferred manner of erection of the carton 11 will now be described. In this regard, the carton iserected by upward folding of the opposed side and end walls along the respective score lines joining the wall panels to the bottom panel; As the four wall panels are formed in upright condition, the gussets, as shown in FIGURE 2, are folded upon themselves along the fold line 57 and are extended outwardly of the adjacent side and end walls, being folded along the appropriate" fold line extensions.

The gussets may, of course, be folded overeither' the side or end walls, or may be folded inwardly of the carton and then into adjacent relation with either of the side or end walls to lock the carton in upright condition- In the carton and thereby provide leak-proof features; 11 illustrated in'FIGURE 2, the gussets 49 and 51, adjacent the front side wall 17 are'fol dedinoverlying'rela tion to thetop and side marginal portions of the front side wall to placethe tabs 59 in overlying relation to the associated slit formations63 in the flap'45. In'this'connection, it will also be noted that the fold line 61 hingedly' connected with the associated slit formations in the same" manner, although the manner of interconnection may be" varied from gusset to gusset; A descriptionof the in terengagernent of the flap 45" with the-tab 59" of one of the gussets' 49 will'be suflicient' to illustrate the manner inwhich' each of the gnssetsis interlockedto'the' adjoining carton wall; In this connection, the tab 59 is'located' in overlying relation to theslit formation 63" and is' inserted over the lower displaceable portion 71" and between the parallelcut lines 65" and 67topo'sitioti thetab side marginal portions on the underside" of the fiap 45. Although the upper displaceable'portion' 73' of the slit formation 63* isfi'rst inwardly directed during insertion of the tab 59, the'pas'sage' of the outer edge of the tab clears. the bottom edge of the upper displaceable portion and allows the portion-73' to return to its originalp'osition in generally co-planar relation with the surrounding" flap panel. At the same time, the lower displaceable portion 71" urges the tab 59 into adjoining underlying. relation with the areasofth'e'flap panel marginal'toth'e" portions 71 of the slit formations to act upon'the centralareaof the tabs withincrea'sed' pressure'to-urg'e'the tabs intocloselocking contact'with the flap 45-; At 'the same time, the upper or covering displaceable portions 73 of the flap slit formations are'caused to assume anoverlying position relative to the upper marginal po'rtion's of the interconnected tabs. Accordingly an'y gap thatmay exist between the tabs and the flap is eliminatedi It -will' be observed, that when the-flap'4'5 is folded in" generally parallel relation to=the bottom panel, as shown in FIG- URE-2, the outer side marginal portions of the tabs5-9 extend under the adjacent regions of the flap 45 and the upper marginal tab portions extend under the upper displaceable portions 73.

A similar arrangement results between the tabs 59 interlocked with the cover panel 33 when the panel is K downwardly folded to effect closure of the carton.

Inward folding of the flap 45 also results in the formation of the slot 87 between the central segment of the :slit 85 and the front side wall 17. Accordingly, when the cover panel is folded downwardly over the carton, the locking tuck 77 may alsobe folded inwardly along :the foldline 79 and located with its outer edge in the slot 87 formed by the inward folding of the flap 45. Downward pressure on the cover panel causes the convergentside edges of the cover tuck 77 to be cammed by the curved portions 89of the flap slit into the extending segments ,87 which are in alignment with the fold line 47. When the tab is fully inserted within the slit 85, the ears 8 3 of the locking tuck snap under the flap 45 into locking engagement. A very effective locking action is thereby p odu eding the improved locking arrangement of the present invention. The carton is erected from the blank 99 shown in FIGURE 3, and in this connection, the reference numerals which apply to the panels of the blank also apply to .the corresponding panels of the carton. The carton '97 includes .a bottom panel 99-hinged along suitable fold lines to -.a front and rear side wall panel 101 and 103, respectively, and to a pair of end wall panels 105 and 107. Each of the end wall panels 105 and 107 is respectively provided with a flap 109 and 111. 'Foldably extending from the rear side wall panel 103 is a cover panel .113, which, in turn, is foldably connected to an outwardly extending cover tuck or flap 115.

Located at each of the corners of the bottom panel is a ,corner member or flap 1=17, 119, 121 and 123, each of which includes a locking tab 125. The corner members 117 and 119 are foldably connected to the front side wall panel 101 along extensions of the fold lines joining the end wall panels to the bottornpanel. The corner members 117 and 1 19 are severed from the adjacent end wall panels by means of the respective slits 127 and 129', which are in general alignment with the fold line joining the front side wall panel with the bottom panel. The corner member 121 is foldably joined to the end wall panel 105 along an extension of the fold line connecting the rear side wall panel to thebottom panel, and is severed from the adjacent rear side wall panel by a cut 131 in general alignment with the fold line connecting the endlwall panel 105 to the bottom panel. The remaining corner member "123- is foldably connected to the end wall panel 107 along an extension of the score line joining the'bottom panel and the rear side wall panel, and is severed from the rear side wall panel by a cut 133 in general alignment with the fold line joining the bottom panel 99 to the end wall panel 107.

The end wall flaps 109 and 111 and the cover panel '113 are each provided with H-shaped slit formations 135 for interengagement with the tabs 125 provided on the corner members. The configuration of the tabs 125 and .H-shaped slit formations 135 is substantially the same as that described with regard to the tabs'59 and slit formations 63 of the carton 11 ('FIGURESI and 2').

As seen in FIGURE 4, the carton is erected by'folding the wall panel into upstanding relation to the bottom paneland by folding and locking of the corner members erected may be cut and formed on ordinary carton manucartons.

the adjoining end wall by engagement of the tabs with the H-shaped slit formations 1'35 of the end wall flaps 10-9 and 111. The other two corner members 121 and 123 adjacent the rear side wall are folded intooverlying relation therewith and interlocked by means .of the tabs 125 with the associated H-shaped slit formations of the top cover panel.

An alternate method of locking the tabs 125 with the disclosed H-shaped slit formations 135 is illustrated in FIGURE 4. In this regard, the tabs 125 are inserted by displacement of both the upper and lower displaceable portions of the H-shaped slit formations 135 to effect disposition of the side marginal portions of the tabs through the parallel cut lines and into interlocking relation with the adjacent under surfaces .of the 'fiaps or cover panel as the case may be. In this arrangement, both the upper and lower displaceable portions underlie the inner surface of the tabs and cause the side marginal portions thereof to be locked to the engaging portions of the flaps or cover panel. This arrangement for locking the tab within the slit formations produces :a vvery neat appearing lock in which there is no gap regardless of whether the locking panels are in upright relation or folded with respect to the adjoining walls.

Thecarton 97 is also illustrative of an alternate method of effecting a lock between the cover panel and the remainder of the carton. In this regard, the clocing tuck 115 extends substantially the entire width of the cover panel 113, and includes a pair of locking ears 137 provided, as illustrated, adjacent the opposite ends of the tuck. The forward side edge 139 of the end wall flaps are formed, as shown, to engage with the locking ears 137 of the tuck to effectively hold the cover panel in snugly closed and locked relation.

The cover and corner member locking arrangement .described in regard to the carton 97 provides for the interengagement of each of the end Wall flaps 109 and 111 "with one of the front corner members and with one of the ears of the cover tuck. The interlock thereby produced ufacture, easy to assemble, and which results in a very neat appearing interlock without an undesirable gap in the outer surface. It should be understood, however, that it is not intended to restrict the application of the disclosed novel locking structure for use only with folding The described lock may be advantageously employed whenever it is desired to fasten together two overlying sheets of flexible sheet material.

Both disclosed cartons are locked in erected condition by employment of the improved locking structure described herein to prevent the possibility of collapse and consequential spillage of the contents of the carton.

Moreover, the arrangement employed in each of the cartons effects engagement of the cover panel in closed and interlocking relation with the flap or flaps which cooperate to retain the carton in erected condition. A sturdier container capable of withstanding severe abuse is thereby formed by this type of construction. In addition, this type of carton construction provides for a neat and square package which may be readily Wrapped with a thin outer sealing covering, as is often done. Moreover, the blanks from which the disclosed cartons are facturing equipment. Erection of the cartons may also be easily achieved 011 simple mechanical equipment similar to that disclosed in the co-pending application Serial No. 687,980 assigned to the assignee of the present invention.

Other additional changes and modifications may be made in the disclosed construction to achieve certain of the features mentioned herein without departing from the principles of the present invention.

1 claim:

l. A folding box comprising a bottom; opposite side walls articulated to said bottom; opposite end walls articulated to said bottom and meeting the side walls at the corners; gussets interconnecting said walls at the corners, each gusset comprising two gusset panels articulated to each other along a diagonal gusset fold line, one of the gusset panels being articulated to a side wall, the other gusset panel of the same gusset being articulated to the adjacent end wall, said gusset panels being folded face-to-face and folded flat against one of said walls, whereby one gusset panel is exposed and the other gusset panel lies between the exposed panel and said one wall; and a corner interlock, said interlock comprising, as a first element, a substantially T-shaped tab comprising a head portion and a neck portion, narrower than said head portion, along which the head portion is articulated, the line of articulation being substantially in line with the top of said one wall panel, considering the box in assembled condition, and, as a second element, a top panel, one of said elements extending from said exposed gusset panel, the other element extending from said one wall, said second element extending from a hinge line defining the top 'of the box and having two spaced lateral cuts therein extending in a direction substantially transverse to said hinge line and a further out between said lateral cuts, said cuts defining an internal tongue pointing away from said hinge line which, upon deflection along a crease substantially in line with said hinge line, exposes an aperture in said top panel, said tab being wider than the distance between said lateral cuts, the width being so dimensioned as to render the tab forceable without permanent creasing from a position overlying said top panel and tongue, by pressure exerted substantially normal to the plane of the tab, through said aperture into a position overlying the opposite side of said top panel to engage with its wider head portion the other panel side substantially at said hinge line, said top panel and tab being folded in the completed box into a position substantially parallel to said bottom.

2. A folding box comprising a bottom; opposite side walls articulated to said bottom; opposite end walls articulated to said bottom and meeting the side walls at the corners; gussets interconnecting said walls at the corners, each gusset comprising two gusset panels articulated to each other along a diagonal gusset fold line, one of the gusset panels being articulated to a side wall, the other gusset panel of the same gusset being articulated to the adjacent end wall, said gusset panels being folded faceto-face and folded flat against one of said walls, whereby one gnsset panel is exposed and the other gusset panel lies between the exposed panel and said one wall; and a corner interlock, said interlock comprising a tab on said exposed gusset panel, and a top panel articulated to said one wall along a hinge line, said top panel having two spaced lateral cuts therein extending in a direction substantially transverse to said hinge line and a further out between said two lateral cuts, said cuts defining at least one internal tongue which, upon deflecton, exposes an aperture in said top panel, one side of said aperture be- 7 ing substantially in line with said hinge line, said tab being substantially T-shaped and comprising a head portion wider than the distance between said lateral cuts, said tab further comprising a neck portion narrower than the head portion, along which neck portion the tab is articulated to said exposed gusset panel, the line of articulation being substantially in line with said hinge line, considering the box in assembled condition, the width of the head portion being so dimensioned as to render the tab forceable without permanent creasing from a position overlying said top panel and tongue, by pressure exerted substantially normal to the plane of the tab, through said aperture into a position underlying said top panel to engage with its wider head portion the other panel side substantially at said hinge line, said top panel and tab being folded in the completed box into a position substantially parallel to said bottom.

3. A folding box comprising a bottom; opposite side walls articulated to said bottom; opposite end walls articulated to said bottom and meeting the side walls at the corners; gussets interconnecting said walls at the corners, each gusset comprising two gusset panels articulated to each otheralong a diagonal gusset fold line, one of the gusset panels being articulated to a side wall, the other gusset panel of the same gusset being articulated to the adjacent end wall, said gusset panels being folded face-to-face and folded flat against one of said walls, whereby one gusset panel is exposed and the other gusset panel lies between the exposed panel and said one wall; and a corner interlock, said interlock comprising a tab on said exposed gusset panel, and a top panel articulated to said one wall along a hinge line, said top panel having two spaced lateral cuts therein extending in a direction substantially transverse to said hinge line and a further cut between said lateral cuts, said cuts being substantially in the shape of an H and defining an upper internal tongue remote from said hinge line and a lower internal tongue between said upper tongue and said hinge line, said tongues exposing upon deflection an aperture in said top panel, one side of the aperture being substantially in line vwith said hinge line, said tab comprising a head portion wider than the distance between said lateral cuts, and a neck .portion narrower than the head portion along which neck portion the tab is articulated to said exposed gusset panel, the line of articulation being substantially in line with said hinge line, considering ,thebox in assembled condition, the width of the head .to said bottom. t p

. 4. A folding box comprising a bottom; opposite side walls articulated to said bottom; opposite end walls articulated to said bottom and meeting the side walls at ,the corners; gussets interconnecting said walls at the corners, each gusset comprising two gusset panels articulated to each other along a diagonal gusset fold line, one of the gusset panels being articulated to a side wall, the other gusset pauel'of the same gusset being articulated to the adjacent end wall, said gusset panels being folded face-to-face and folded flat against one of said walls, whereby one gusset panel is exposed and the other gusset panel lies between the exposed panel and said one wall; and a corner interlock, said interlock comprising a tab articulated to said exposed gusset panel; and a top panel articulated to said one wall along a hinge line, said top panel having two spaced lateral cuts therein extending'in a direction substantially transverse to said hinge line, and a further out between saidlateral cuts, said cuts being substantially in the shape of an H and defining an upper internal tongue remote from said hinge line, and a lower I internal tongue articulated at said hinge line, said tongues exposing, upon deflection, an aperture in said top panel,

said tab comprising a head portion of a height to extend .beyond said lower tongue to overlap a marginal portion of said upper tongue adjacent said further cut, the head portion being of a width greater than the distance between said lateral cuts, and a neck portion narrower than the head portion along which neck portion the tab is articulated to said exposed gusset panel, the line of articulation being substantially in line with said hinge line, considering the box in assembled condition, the width of the head portion being so dimensioned as to render the tab forceable without permanent creasing from a position overlying said top panel and upper tongue, by pressure exerted substantially normal to the plane of the tab, through said aperture into a position underlying said top panel and said upper tongue to engage the other panel side substantially at said hinge line, said top panel and tab being folded in the completed box into a position substantially parallel to said bottom.

5. A folding box comprising, in combination, a bottom; opposite side walls articulated to said bottom; opposite end walls articulated to said bottom and meeting the side walls at the corners; a cover panel articulated to one of said side walls; a front flange articulated to the other side wall; gussets interconnecting said walls at the corners, each gusset comprising two gusset panels articulated to each other along a diagonal gusset fold line, one of the gusset panels being articulated to a side wall, the other gusset panel of the same gusset being articulated to the adjacent end wall, said gusset panels being folded faceto-face and folded fiat against said side walls, whereby said other gusset panel is exposed and said one gusset panel lies between the exposed panel and the respective side wall; and a corner interlock, said interlock comprising a tab on said exposed gusset panel in a position to overlap said front flange and said cover panel, respectively, said front flange and said cover panel having two spaced lateral cuts therein extending in a direction substantially transverse to the hinge lines along which the front flange and the cover panel are articulated to the respective side walls, and a further out between each two lateral cuts, said cuts defining at least one internal tongue which, upon deflection, exposes an aperture in the respective cover panel and front flap, said tab being wider than the distance between the two lateral cuts which it overlies, the width being so dimensioned as to render the tab forceable without permanent creasing from a position outside the cover panel and front flange by pressure exerted substantially normal to the plane of the tab through the respective aperture into a position underlying the cover panel and front flange, respectively, to overlap the other side of said cover panel and front flange adjacent said lateral cuts, said cover panel and front flange lying substantially parallel to said bottom in the closed box in which position said tabs pull the respective exposed gusset panels tight against the side walls by reason of being folded with respect to the exposed gusset panels at a larger radius than said cover panel and front flange with respect to the side walls to which the cover panel and front flange are articulated.

6. A folding box comprising, in combination, a bottom; opposite side walls articulated to said bottom; opposite end walls articulated to said bottom and meeting the side walls at the corners; a cover panel articulated to one of said side walls; a front flange articulated to the other side wall; gussets interconnecting said walls at the corners, each gusset comprising two gusset panels articulated to each other along a diagonal gusset fold line, one of the gusset panels being articulated to a side wall, the other gusset panel of the same gusset being articulated to the adjacent end wall, said gusset panels being folded faceto-face and folded flat against said side walls, whereby said other gusset panel is exposed and said one gusset panel lies between the exposed panel and the respective side wall; and a corner interlock, said interlock comprising a tab on said exposed gusset panel in a position to overlap said front flange and said cover panel, respectively, said front flange and said cover panel having two spaced lateral cuts therein extending in a direction substantially transverse to the hinge lines along which the front flange and the cover panel are articulated to the respective side walls, and a further out between each two lateral cuts, each two lateral cuts and the further out therebetween being substantially in the shape of an H defining an upper internal tongue remote from the hinge line of said cover panel and said first flap, respectively, and a lower internal tongue between said upper tongue and the respective hinge line, said tongues exposing, upon deflection, an aperture in the respective cover panel and front flange, said tab being of a height to extend beyond the respective lower tongue to overlap a marginal portion of the upper tongue adjacent said further out and being of a width greater than the spacing of said lateral cuts which it overlies, the width being so dimensioned as to render the tab forceable without permanent creasing from a position outside the cover panel and front flange by pressure exerted substantially normal to the plane of the tab through the respective aperture into a position underlying the cover panel and front flange, respectively, to overlap the other side of said cover panel and front flange adjacent said lateral cuts, said cover panel and front flange lying substantially parallel to said bottom in the closed box in which position said tabs pull the respective exposed gusset panels tight against the side walls by reason of being folded with respect to the exposed gusset panels at a larger radius than said cover panel and front flange with respect to the side walls to which the cover panel and front flange are articulated.

References Cited in the file of this patent UNITED STATES PATENTS 407,49'4- Schwartz July 23, 1889 556,675 Howe Mar. 17, 1896 613,520 Keys Nov. 1, 1898 997,116 Chase July 4, 1911 1,672,251 Fox June 5, 1928 2,103,382 Petter Dec. 28, 1937 2,667,297 McReary Jan. 26, 1954 FOREIGN PATENTS 398,044 Great Britain Sept. 7, 1933 

